The present invention generally relates to a winding arrangement, and more particularly, to a winding apparatus for electric wires and the like, which is equipped with a device for properly adjusting tension applied to a wire, during winding of the wire continuously discharged through a nozzle of a flyer member and wound onto a winding form or winding frame, and which may be particularly employed as part of a manufacturing arrangement, for example of coils of electric rotary machines, etc.
Referring first to FIG. 1 showing a conventional winding apparatus, constructions and functions of a flyer and a tension applying device incorporated therein will be described hereinbelow.
In FIG. 1, the winding apparatus generally includes the tension applying device T for adjusting the tension of a wire 3 wound on a bobbin 4 and passed through said device T, and a wire passage 5 in the form of a tube for leading the wire 3 from the tension applying device T towards the flyer 1 through a main body 15 of the winding apparatus. The flyer 1 is provided with guide rollers 12 and 13 incorporated therein for further guiding the wire 3 into a nozzle portion 14 formed at a distal end of one of a pair of flyer arms 1a extending downwardly from opposite end portions of a flyer base 1b, with said flyer 1 being arranged to be rotated around a winding form or winding frame 2 by a shaft S extending from a motor M to the flyer base 1b through the main body 15 of the winding apparatus and a boss portion B as shown for winding the wire 3 fed out through the nozzle portion 14 onto the winding form 2.
The tension applying device T further includes guide members 7, 10 and 11 accommodated in a housing Ta in spaced relation from each other. Each of the guide members 7, 10 and 11 has an opening for passing the wire 3 therethrough, while the guide member 7 supported on a base 9 and the guide member 10 are each formed with other sets of openings provided to surround the wire passing openings thereof for passing therethrough a tension applying thread 6 which is twisted together between the members 7 and 10 for imparting a tension to the wire 3 in a manner as described later. Accordingly, the wire 3 paid out from the bobbin 4 is led through the guide members 11, 10 and 7 and the twisted portion of the thread 6, and further, the wire passage 5, and then, guided by the rollers 12 and 13 so as to be fed out through the nozzle portion 14 and wound onto the winding form 2 as the flyer 1 rotates.
In the above arrangement, for winding the wire 3 onto the winding form 2, it is generally required to apply a tension to the wire 3. For this purpose, it is so arranged that the wire 3 is squeezed by further twisting the thread 6 through turning of the guide member 7 by loosening a bolt 8 which secures said guide member 7 normally in position. In the above state, the tension thus imparted is actually measured by a tensiometer or the like as the wire 3 is drawn out from the nozzle 14, and upon application of a sufficient squeezing equivalent to a proper tension to the wire 3, the guide member 7 is fixed in position by tightening the bolt 8. For altering the tension to be imparted, the bolt 8 is again loosened, and the guide member 7 is rotated to alter the degree of twisting of the thread 6, with subsequent re-tightening of the bolt 8.
However, in the conventional practice as described above, there is a disadvantage that, since the distance ranging from the thread 6 to the winding form 2 is considerably long, the wire 3 is kept stretched or elongated for a long period of time while it is passing therebetween, thus resulting in an increase in its elongation. Therefore, in the conventional method, it has been impossible to fully meet the demand for minimizing the elongation of the wire from the viewpoints of characteristics and manufacturing technique, for example, as required in coils for electric motors, etc.
When a smooth regular winding is particularly required for winding the wire 3 onto the winding form 2, it is necessary to impart a certain predetermined tension to the wire 3. However, in general, since the winding form 2 does not have a circular cross section, the speed of the wire 3 to be fed out during one rotation is varied to a large extent, while a marked variation is also noticed in the speed at which the end of the winding is paid out from bobbin 4.
In the conventional arrangements, when the speed at which wire is paid out is suddenly raised in the above-described manner, since the wire 3 is abruptly pulled while being held by the thread 6, a large tension is exerted thereon, while on the contrary, upon rapid reduction in the speed, the wire is brought into a sagged state while being held by the thread 6, with a consequent rapid reduction in the tension. In other words, in the conventional winding apparatuses, it has been impossible to apply a constant tension. Moreover, for altering the tension to be applied, it has been necessary to make adjustments so as to achieve the required tension by actually measuring the tension through alterations of the degree of twisting of the thread 6 on a trial and error basis.